1. A car of mass 1167kg accelerates on a flat highway from 10.0 m/s to 28.0 m/s.
ID: 1396980 • Letter: 1
Question
1.
A car of mass 1167kg accelerates on a flat highway from 10.0 m/s to 28.0 m/s. How much work does the car's engine do on the car?
210 kJ
399 kJ
942 kJ
18.3 kJ
2.
An adult generates 72 W of power as she pulls a sled forward across a flat snowy surface with a force of 80 N. The adult pulls with this force for 4.5 minutes. What distance does the sled move?
180 m
130 m
240 m
280 m
3.
A child does 350 J of work against gravity as she pulls a box from the ground up to a tree house with a rope. The tree house is 5.0m above the ground. What is the mass of the box?
7.1 kg
5.3 kg
4.3 kg
6.4 kg
4.
An apartment dweller runs a 120-W stereo system for 16 hours a month, on average. The landlord reduces the cost of electricity by 0.37 cents/kWh. How much money will the apartment dweller save per year?
2.4 cents
32 cents
8.5 cents
0.71 cent
5.
The graph shows the relationship between a force acting on an object and the displacement of the object. To which situation does the graph best apply?
a car accelerating at a constant rate along a flat highway
a car traveling at a constant speed along a flat highway
a rock tossed at an angle off the roof of a tall building
a spaceship increasing its rate of acceleration through space
6.
A model rocket with a mass of 0.212 kg is launched into the air with an initial speed of 84 m/s. How much kinetic energy will the rocket have at a height of 214 m? Assume there is no wind resistance.
303 J
747 J
634 J
444 J
7.
A tennis ball is released from a height of 2.0 m above the floor, and then bounces three times. With each bounce, dissipative forces cause it to lose 16.0% of its mechanical energy. How high does it reach after the third bounce?
120 cm
120 mm
140 cm
12 cm
8.
A spring is compressed to a displacement of -3.9 m from equilibrium. Then the spring is released and allowed to stretch to a displacement of -1.5 m from equilibrium. The spring constant is 11 N/m. What best describes the work involved as the spring stretches?
The spring performs 140 J of work
140 J of work is performed on the spring.
71 J of work is performed on the spring.
The spring performs 71 J of work.
9.
Which is an example of a nonconservative force?
friction
elastic force
gravity
electrostatic force
10.
A student releases a rock of mass m from a height h above the ground. Values for which set of variables are essential to calculate the speed at which the rock strikes the ground? Assume that the acceleration due to gravity (g) is known, and that the effect of air resistance and other nonconservative forces are negligibly small.
m, but not h
neither h nor m
h and m
h, but not m
1.
A car of mass 1167kg accelerates on a flat highway from 10.0 m/s to 28.0 m/s. How much work does the car's engine do on the car?
210 kJ
399 kJ
942 kJ
18.3 kJ
2.
An adult generates 72 W of power as she pulls a sled forward across a flat snowy surface with a force of 80 N. The adult pulls with this force for 4.5 minutes. What distance does the sled move?
180 m
130 m
240 m
280 m
Explanation / Answer
1)
here
KE1 = 0.5 * m * vi^2
KE1 = 0.5 * 1167 * 10 * 10
KE1 = 58350 J
then the final
KE2 = 0.5 * m * vf^2
KE2 = 0.5 * 1167 * 28 * 28
KE2 = 457464 J
therefore
W = KE2 - KE1
W = 457464 - 58350
W = 399114 J = 399 kJ
so the work done is 399 kJ
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